This invention relates to a method for manufacturing graphic products such as designs or characters for signs and the like, and an apparatus for performing the method. The types of graphic products to which this invention is directed are characters or designs which adhere to a backing or substrate. The manufacturing of these types of graphic products generally involves the steps of cutting the graphic product from a layer of sheet material on a carrier sheet, removing the product from the carrier sheet and then attaching the product to the substrate.
The present invention is directed to an automated method and apparatus for removing such graphic products from the carrier sheet and includes the selective removal of either the weed interlaced with the product or the graphic product itself. The invention also includes a unique heat activated bonding web for use with the method and apparatus.
The removal of weed and a graphic product, such as a group of spaced letters cut from a layer of sheet material on a carrier sheet for transfer of the product to a substrate, has hitherto been a tedious, time consuming, and usually manually performed job. Frequently, tweezers are used for removing small areas of internal weed such as the center of the letter "A" or "R" from the body of the letter. In addition, the larger external weed, the material surrounding the letter bodies, has also been removed in the same manner. After the weed is removed, the transfer of letters from the carrier sheet to a substrate has been accomplished by manually attaching a transfer web to the graphic product, pulling the web and attached product away from the carrier sheet and placing the web and product into proper position for attachment to a sign substrate. The transfer web is then stripped away from the product. A transfer method and web with a dry activatable adhesive for such purposes is disclosed in U.S. Pat. No. 5,026,584 to Logan, having the same assignee as this invention.
The sign making field includes apparatuses and methods for automated sign making, and includes automatic weeding systems and methods. For example, U.S. Pat. No. 5,143,576 issued on Sep. 1, 1992 to Logan and owned by the assignee of the present invention discloses an apparatus and method for automating weed removal. The apparatus uses stored data in the form of vectors for attaching a bonding web comprising adhesive microcapsules to a graphic product or weed on a carrier sheet along a linear path offset from the periphery of the weed or graphic product In the apparatus, a pressure applicator tool activates the adhesive microcapsules within the web to temporarily bond the web to the graphic product or weed based on the stored data defining the periphery of the graphic product or weed.
The linear nature of the adhesive bond formed by the apparatus in U.S. Pat. No. 5,143,576 omits large portions of the surface area of the graphic product or weed, and thus allows limited or unbalanced forces to be applied to the weed or graphic product upon removal from the carrier sheet with the possibility of tearing the graphic product at the unbonded areas. In contrast, the instant invention bonds the web to substantially the entire surface area of the graphic product or weed, and thus allows the adhesive forces to be distributed throughout the graphic product or weed surface. Moreover, the instant invention is compatible and complementary to automated printing devices and cutters having similar feed mechanisms which have already gained popularity in the sign making industry.
U.S. Pat. No. 4,645,555 to Kuboyama discloses a hot stamping method used for the formation of sharp edged characters and/or numerals in a sheet material attached to a base plate for transfer from the base plate to a substrate. That is, raised numerals or characters are joined to a base plate, and a bonding web including a heat activated adhesive is pressed over the substrate and the numerals or letters. Upon heating the sheet material over its entire surface, the raised characters are joined to an adhesive comprising the sheet, and at the areas where no numerals exist the adhesive remains on the base plate. Therefore, heat is applied over the entire surface of the bonding web and base plate for adherence to the entire base plate surface including the surface of the numeral or character. Unlike the present invention, selective heating is not used for attaching the bonding web to the graphic product alone.
U.S. Pat. No. 4,374,691 to Vanden Bergh discloses a material and method for forming pressure transferable graphic designs. The invention includes a composite material and a method of forming characters or numerals in the composite material and removing the same therefrom for attachment to a substrate. The composite material includes a donor layer for supplying the letters or characters and an accepting layer for receiving the letters and characters. One step involves forming the letters and attaching the letters to the accepting layer. The letters are not preformed in a layer of sheet material on a carrier sheet as in the instant invention. Instead the letters are formed in a layer of sheet material on a carrier sheet by applying heat to the accepting sheet over the desired graphic design formation. The accepting sheet includes an adhesive which is activated upon heating, and during contact with the donor sheet, the adhesive causes sections of the donor sheet to attach to the accepting sheet in configurations resembling the graphic designs drawn. The donor sheet is comprised of a material which is easily fragmented and upon the application of the adhesive, sections matching the graphic designs adhere to the accepting layer. The graphic design may then be removed from the donor sheet and is pressure- or heat- transferred to a sign substrate. Unlike the instant invention, the patent to Vanden Bergh does not incorporate selective activation of a bonding web for registration with, and for joining to precut graphic products.
U.S. Pat. No. 5,112,423 to Liebe Jr. discloses a method of making and applying alignment maintaining plastic lettering material. The method in Liebe uses a composite sheet of material comprising an adhesive layer, a display layer and a release layer. The method includes cutting graphic letters or numerals and the like into the adhesive and display layer but not into the release layer, and stripping away the adhesive and display layers not within the desired outline of the numerals, letters or other graphic product. Accordingly, the release layer is left with the lettering thereon for transfer to a substrate. Unlike the instant invention, selective activation and attachment of a bonding web is not used for removing the symbols or letters from the release layer.
In addition to the above patents using an adhesive for pulling or separating letters or numerals or the surrounding areas from a donor sheet, the art also includes patents directed toward the application of a release layer to a layer of a donor sheet to cause sections of the donor to remain on a carrier sheet while separating other sections. For example, U.S. Pat. No. 4,933,124 to Duncun discloses a process for applying a silicon release coating to a polymer film. The Duncun process includes the application of a release film onto a substrate but the selective automated application of such a film to particular areas of the substrate using a selectively activated head is not disclosed.
As discussed above, the invention also includes a laminated bonding web material having a heat sensitive adhesive and a friction reducing coating thereon for easing the advancement of the web across a heating head in practicing this invention. While U.S. Pat. No. 5,082,822 to Uytterhoeven et al. discloses a die donor element having a coating thereon for easing the passage of a sheet material under a thermal head during printing applications, such a material has not been uncovered with respect to selectively activated adhesive webs as disclosed herein.
The manufacturing and demand for signs comprising letters or designs has become increasingly popular in the sign manufacturing field. In combination with enhanced printing, the resulting graphic products have many applications. With this invention, the removal of graphic products and weed from a carrier sheet by means of a bonding web is no longer a tedious and difficult task. Manual labor including the use of tweezers for removing weed and graphic products from the carrier sheet for transfer of the graphic product to a substrate has been replaced by automation.
Accordingly, one object of this invention is to provide a highly accurate method and apparatus for automated removal of characters and other graphic products or the weed associated therewith from a carrier sheet by selectively attaching a bonding web for convenient transfer of the product to a sign substrate.
A further object of this invention is to provide a method and apparatus for accomplishing automated weeding and graphic product removal without risk of tearing the graphic products.
A still further object of this invention is to provide an automatic weeding and graphic product transfer apparatus and method that are compatible with and complementary to existing successfully marketed sign manufacturing equipment.